1. Field of the Invention
The present general inventive concept relates to a disk drive apparatus and a control method, and more particularly, to a method and apparatus to correct a phase difference of a servo sector due to rotational slip between disks in a disk drive apparatus.
2. Description of the Related Art
Korean Patent Publication No. 1994-16175 and Japanese Patent Publication No. 1996-180660 disclose technology related to a hard disk drive. Korean Patent Publication No. 1994-16175 describes converting a disk surface to be processed and accurately following the eccentricity of the converted disk surface, when a plurality of disk surfaces are present in a disk drive. Japanese Patent Publication No. 1996-180660 describes reading a plurality of disks in a disk drive using respective heads and correcting the phase of a sync timing signal by detecting an interactive rotational phase difference.
A hard disk drive apparatus (HDD) is a data storage device which stores data on a disk using a magnetic head, and is integral to many computer systems. As HDDs improve they become highly dense and compact. This is measured in BPI (bits per inch) which is the density in the direction in which the disk rotates, and TPI (tracks per inch) which is the density in the radial direction of the disk. As these parameters increase, more accurate mechanisms are required.
Since the number of tracks increases as the recording density of the HDD increases, a longer time is needed to write servo information on the disk. To solve this problem, an offline servo track write (STW) method has been developed, for writing servo information on a plurality of disks at the same time using external equipment, without coupling the disks.
The HDD often includes a plurality of disks to increase recording capacity. Accordingly, if the HDD is assembled by performing servo write in the offline STW method, the position of a servo sector varies between the disks in the rotational direction. Also, the position of the servo sector between disks can be changed in the rotational direction by an external impact. This phenomenon is referred to as rotational slip, and can change the phase of a logical data sector during disk switching.
When a logical data sector number is assigned during the disk switching without considering disk rotational slip, the phases of the logical data sectors do not match, and data read and write performance deteriorates.